[Reprint from The St. Louis Medical and Surgical Journal, June, 1893.] 
THE 
COMMONER ANIMAL PARASITES 
OF THE SKIN, 
BY /' 
/ 
A. II. OHMANN-DUMESNIL, A. M., JI. D., 
ST. LOUIS. MO. The Commoner Animal Parasites of the Skin.* By A. H. 
Ohmann-Dumesnil, St. Louis, Mo. 
It has been my custom, when giving instructions in the diagnosis 
of diseases of the skin, to call the attention of students to one 
point in particular. Before mentioning this more definitely, I 
will premise by stating that a prominent subjective symptom is, 
beyond all doubt, itching. It is not only more annoying to the 
patient, but it also fosters the production of more or less de- 
struction of the upper layers of the integument through the 
scratching which is indulged in to relieve the irritation. Itching 
is frequently the only symptom of the trouble, as is the case in 
pruritus, but the attempts to relieve this produce eruptions which 
only tend to obscure the diagnosis for those who are not well ac- 
quainted with the subject. In addition to this, there is a preva- 
lent idea, that when a patient has an itching eruption, whether 
it be primary or secondary in character, it must necessarily be 
eczema, this misconception having originated from the dual fact 
that eczema is polymorphous in character, and prevails to a very 
large extent. Nor is this all. Another fallacy which is com- 
♦Read before the Missouri State Medical Association, May, 1893. 2 
mon, and it has unfortunately been fostered by those who should 
know better, is that syphilitic eruptions never itch; when, as a 
matter of fact, they frequently do, when occurring in hairy por- 
tions. I have alluded to these two affections more particularly 
because they have an important bearing upon the subject I pro- 
pose to discuss. 
To return to my first proposition. The point to which I es- 
pecially direct attention is this: Whenever a patient complains of 
itching of the integument, no matter where this may be felt, 
always begin your formulation of a diagnosis by a careful search 
for parasites, either vegetable or animal; and, in case such are 
found, . immediately direct your therapeutic measures to the 
prompt destruction of these. For it is absolutely necessary to 
secure a disappearance of these irritants in order to obtain any 
satisfactory change in a cutaneous disease. Permit such active 
irritation to remain uncared-for, and it will increase in propor- 
tion to the increase in the number of parasites; and, as I will point 
out later on the multiplication in the case of animal forms, at 
least, is in a direct geometrical proportion explaining the oft-times 
almost remarkable multiplication of the little living pests which 
frequently cause, not only local discomfort, but may even directly 
endanger a human life through the causation of loss of sleep, 
the continued maintenance of nervous irritability and consequent 
derangement of all the functions of the economy leading to per- 
verted nutrition, loss of tone, and susceptibility to general dis- 
eases and pathological conditions of a more or less grave nature. 
We have in addition to this the direct loss of blood occasioned 
by the withdrawal exercised by the predatory parasites, a source 
of debility which is added to by the artificial losses caused in 
the fruitless attempts of the patient to relieve the itching. We 
have still more to note in this direction-the destructive lesions 
which are produced in many instances suppurate, and in that 
manner not only produce a direct loss of tissue, but furthermore 
may bring mischief in the way of absorption of poisonous or 
effete products. Finally, the parasites themselves are but too 
frequently the carriers of micro-organisms, not only on the surface 
of their bodies, but in the proboscis. For it is a well-known 
fact, that they feed upon bacteria, and when they drive their 
delicate pumping apparatus into the skin, in their search for 3 
blood, they propel an alkaline liquid which has the power of 
liquefying the blood, and thus they convey these organisms into 
the lymph spaces of their victims. My hearers may remember 
the report of a recent case of tuberculosis which was traced to 
bed-bugs, and they are also aware of the claims which have been 
made, with some show of justice, of mosquitoes being the active 
propagators of yellow' fever. 
I do not propose to speak of all the animal parasites which 
infest the skin, but I intend to take under consideration a few of, 
those which are of more especial interest to the physician. To 
take a survey of all the animal parasites which irritate the skin 
would necessitate the compilation of a volume, and would more- 
over necessitate such a complete survey of the field as would 
hardly be justifiable under the circumstances. For this reason I 
will only take into consideration the acarus scabiei, the various 
pediculi, the pulex irritans, the cimex lectularius, the ixodes, and 
chicken louse. The rarer forms as wrell as those not so intimately 
connected with the lesions of the skin will not be considered, in 
order to keep this paper within the limits assigned to it by the 
time afforded in its reading. 
In the consideration of each of these parasites I propose fol- 
lowing a certain plan, which will be about as follows: The salient 
points of the eruption will be described, inclusive of the portions 
most frequently affected, followed by a notice of the habitat of 
the parasites. In conclusion, a description of this latter will be 
given, together with such information in regard to its natural his- 
tory as will prove of service to the practitioner as well as of in- 
terest to the student. I do not propose to enter into any deep 
disquisition on the subject, but merely to give the more promi- 
nent facts in connection with the subject in the hope that they 
may, in some small measure, prove of service to those wdio may 
consult them. 
In addition to the above, a few words on the treatment of the 
affections caused by the parasites, as well as the methods of de- 
stroying them and preventing their recurrence, will not be inap- 
propriate and may, in some measure, also prove of service to 
those interested in the subject. With these few prefatory re- 
marks, I will begin the consideration of each individual parasite 
which I have mentioned above. 4 
SARCOPTES SCABIEI. 
The eruption occasioned by this parasite is beyond doubt the 
most serious of all the animal parasitic dermatoses which I pro- 
pose to take into consideration. Whilst limited in its area at its 
inception, it spreads very rapidly, chiefly through the efforts at 
scratching by the patient. The typical lesion which is character- 
istic of the presence of the parasite is a vesicle which is the 
abiding place of the female, which burrows under the horny layer 
of the epidermis, whereas the male limits his movements to the 
surface in search of the female. After fecundation, the female 
immediately tunnels underneath the upper layer of the skin for 
the purpose of depositing her ova, which mature as she pursues 
her way, so that by the time the eggs are laid the first one has 
already released its tenant. These furrows have the appearance 
of a small piece of black thread drawn under the skin, the dark 
appearance being caused by the deposits of excrement made by 
the female. Such a cuniculus is easily opened, and by the use 
of a proper magnifying glass the ova may be distinctly made out. 
The burrowing will easily explain the intense itching of the 
trouble as well as account for the fact that the flexures of joints, 
and those portions of the integument which are thinnest, are 
chosen for the purpose of laying eggs. Add to this the fact 
that contagion is the method of acquiring the trouble, no difficulty 
will be experienced in remembering the fact that the skin between 
the fingers and at the flexures of the wrists is that which is gen- 
erally affected. The extension of the trouble is easy and second- 
ary lesions soon appear after establishment of the trouble. The 
vesicles are torn open, the parasite released, the floor of the vesi- 
cle is torn as well as the cuniculus, pustules form, papules de- 
velop as a result of the lesion, crusts form here and there, and 
we have finally presented the picture of an inflammatory, poly- 
morphous eruption of an exudative nature, in which the attacks 
of itching are irregular and intense. So far as the distribution 
of the lesions is concerned, one general rule may be formulated. 
The older the affection, the greater the dissemination. After it 
is once well established, the eruption is most marked in those 
portions which are most accessible to the scratching fingers. One 
of the most common accessory causes in the perpetuation of the 
trouble is filth. An unclean body necessitates scratching to loosen 
the accumulated epidermal scales and thus indirectly aids in the 5 
further dissemination of the parasites. Filthy underwear forms a 
permanent depot for the sarcoptes to lodge in, besides acting as 
a preventive to the thorough action of any remedial measures 
which may be undertaken. Fortunately, the better conditions 
which prevail in this country have done much to lessen the num- 
ber of cases which, to the uninitiated, is truly appalling in the 
large continental cities. Yet during the late civil war in the 
United States scabies was one of the curses with which both 
armies were afflicted. A peculiarity of scabies is that it does not 
affect the face or head. 
The parasite which causes the disease is known as the sarcoptes 
scabiei. It was formerly called the acarus scabiei, from the fact 
that it belongs to the order acarina, family acaridae, class arach- 
noidae. It is a minute roundish animalcule barely visible to 
the naked eye, being equal in surface to the cross section of a 
small pin and pale yellowish in color. The female is much larger 
than the male, varying in length from i to 1and in breadth 
from to The form is somewhat ovalish, the head being 
closely set to the body and also otal in form. There are no 
eyes. The thorax is provided with four short, jointed legs, 
terminating in suckers and bristles. The abdomen is likewise 
provided with similar legs of equal number. In the female the 
abdominal legs terminate in bristles, whereas in the male the 
last pair is also provided with suckers, the other two terminating 
in bristles. In the male we observe the external genital organ 
very plainly, whereas in the female there is a cleft visible at the 
abdominal extremity. When viewed upon its ventral surface 
there may be distinguished a number of cross striations which are 
undulating, and here and there small spinous processes from 
which bristies emerge. The head is provided writh strong mandi- 
bles, and six hairs project from it. The habitat of the female 
is in the skin. As soon as it finds itself upon the integument, 
it begins burrowing to form a cuniculus wherein to lay its eggs. 
The male roams about on the surface looking for females to 
fecundate. The young are very hardy and develop very rapidly, 
the period of incubation varying from eight to ten days. With 
a little care the female sarcoptes can be extracted as well as the 
young in various stages. The male is more difficult to obtain, 
yet a little patient research will generally be rewarded by obtain- 
ing a specimen. 6 
The treatment of scabies consists essentially in the destruction 
of the parasite which is the exciting cause of the trouble. A 
large number of methods have been successfully used to accom- 
plish this purpose, and in such instance the thoroughness of ap- 
plication is the most essential part. From time immemorial the 
specific for scabies has been sulphur, and it has served a good 
purpose when properly applied. I do not propose to give all the 
methods employed, but will merely enumerate a few which are 
efficient. In Paris, where an enormous number of patients are 
treated daily at the Hopital St. Louis, the patients are given a 
hot bath with frictions of black soap (savon noir) and well scrub- 
bed. Then Wilkinson's ointment* is well rubbed in, and the cloth- 
ing, which has previously been subjected to an intense heat in an 
oven, is resumed. One such treatment is sufficient. In Vienna 
the treatment is analagous. It is essential, - however, that the 
ointment be well rubbed in. Another method consists in scrub- 
bing the skin well with soap (sapo viridis) and water, and then 
rubbing in a sulphur ointment containing a drachm of the pre- 
cipitated sulphur to the ounce of fresh lard. A method which is 
cleaner, and which I have successfully employed, is this: The 
patient takes a hot bath with some alkaline soap, in the morning, 
putting on a complete change of clothes. He then applies in the 
interval, i. e., before assuming the change of clothing, and after 
thoroughy drying the skin, the following: 
Pt Sodii hyphosulphit 3 viij- 
Aquae destillat 3 
M. 
After being applied it is permitted to dry on the skin, then 
the clothing is put on. 
In the evening before retiring the following is applied: 
Pt Acid, hydrochloric! dil 3 vj* 
Aquae destillat 3 iv- 
M. 
If it be too severe the acid may be further diluted so as not to 
prove too painful. 
♦Wilkinson's ointment as modified by Hebra is as follows: 
p: Sulfuris, 
Ol. cadini aa 3 ss- 
Sapo viridis, 
Adipis aa 3 j* 
Cretae preparat 5 iiss 
M. 7 
The effect of this treatment is marked, and it possesses sev- 
eral advantages over other methods. It is cleanly in the first 
place. It is easy of application, and it ensures a precipitation 
of sulphur in an exceedingly divided state in every small fissure 
which may exist, thus making it as thorough as it is possible to 
do so. The process should be repeated daily for three or four 
days, not omitting the change of underwear and clothing. The 
clothes temporarily cast off should be subjected to a dry heat 
sufficiently intense to kill any lurking parasites, and yet not so 
high as to scorch the material. A little carefulness exercised in 
this matter will result in a satisfactory result, and no unnecessary 
expense will be incurred by the destruction of clothing. The 
point to be observed, however, is that whatever method be 
adopted make the applications thorough, and further eliminate all 
possible cause of infection. 
PEDICULUS CAPITIS. 
Pediculosis or phthiriasis capitis is an affection which, whilst 
not common in this country, is seen sufficiently often to attract 
more than passing attention. In Europe it is much more fre- 
quent in occurrence, and there, as here, it is among the poorer 
classes, and those who are strangers to cleanliness, that it is more 
frequently observed. A little care in making an examination 
will enable a diagnosis to be easily reached by the fact that the 
parasite is easily seen, as well as its ova. In a mild case of the 
trouble the patient complains of itching in the scalp, and this sen- 
sation is not confined to any one point, but seems to be changing 
its location continually, occasionally occurring in several points 
at one and,the same time. Scratching of a mild character moment- 
arily relieves the pruritus. The hairy scalp alone is affected, the 
parasites confining themselves to this area. To find the little 
pests it is necessary to part the hair, as they limit their roam- 
ings to the integumentary surface, as a general thing. Upon the 
hairs will be found "nits" or ova tightly glued to the shaft, and 
presenting the appearance of minute white bodies or apparent 
nodes. Should the condition have existed some time the multi- 
plication of the pediculi has been so great, and the consequent 
irritation so marked, that scratching is more severe, and as a 
natural consequence, a dermatitis more or less severe in character 
is set up. Papules, pustules, crusts and excoriations exist in 
various proportions accompanied by a glairy exudation which 8 
tends to mat the hair. Fermentative changes set in, and are at- 
tended by a disagreeable foetid odor of a more or less sour smell. 
Add to this the accumulation of extraneous matter and the con- 
dition of extreme filth which is presented can be better imagined 
than described. As a result of scratching low down on the oc- 
ciput we have the pruritus extended some distance down the 
neck, and the efforts made to relieve this produce excoriations 
and crusts of a dirty color, the condition being known as por- 
rigo pediculis. The site of predilection of pediculi capitis is 
the occiput, the vertex, the temples also being favored spots. 
Whilst more frequently observed in those having long hair, it is 
also often observed in those who keep their hair trimmed short. 
It is seen at all ages, and may be easily acquired by those of 
cleanly habits who may come in contact with the persons, cloth- 
ing or bedding of patients having pediculosis. Street cars, rail- 
way carriages, cabs, and other conveyances are a frequent source 
of contamination. 
The pediculus capitis or head louse is grayish in color, of an 
elongated ovalish form. The female is somewhat larger than the 
male, the sizes varying from^'" to 1|" in length, and about one- 
half of this in breadth. The head is somewhat acorn-shaped, 
provided with distinct eyes and five-jointed antennae. The legs, 
which are attached to the thorax, are provided with four joints 
exclusive of the claw with which each one terminates. The legs 
and body are provided with hairs which are quite distinct. Strong 
mandibles exist, and enable the parasite to traverse through the 
stratum corneum of the skin down to the rete malpighii from 
which it can derive its sustenance in the form of blood. The 
habitat of the pediculus capitis is on the scalp; the female, how- 
ever, being frequently found upon the hairs where it goes to de- 
posit its ova for incubation. The ovum or " nit " is a whitish, 
oval or pyriform body about V" in length, and is distinctly visi- 
ble. It is attached to the hair by a peculiar glutinous substance. 
One or more ova may be attached to the same hair. The incuba- 
tion period varies from six days to a week, and the females are 
very prolific being almost continually occupied laying eggs. It may 
be readily seen how an enormous multiplication of the parasite is 
possible in a comparatively short space of time. 
The treatment of pediculosis capitis must not only be curative, 
but prophylactic. In order to obtain a permanent release from Sarcoptes Scabiei. 
Pediculus Capitis. 9 
the pests it is absolutely necessary to remove all causes of pos- 
sible contagion. In order to ensure this, individuals similarily 
affected should be avoided, and all head coverings subjected to a 
process which will effectually destroy the parasites and their ova. 
Combs and hair brushes should likewise be thoroughly cleansed 
after each time they are employed, and no other individual should 
be permitted to use them any more than hats, caps, or similar 
articles of dress. In the case of males affected with pediculi of 
the head, the treatment is comparatively a simple matter, as the 
hair may be clipped very close thus affording an opportunity of 
making applications more thoroughly. All ointments should be 
avoided, as they are disagreeable to use, whereas liquid prepara- 
tions are more agreeable and cleanly. I have found one of the 
best remedies to employ for this purpose in campho-phenique 
which not only kills the parasite and destroys the ova rapidly, 
but has the further effect of acting as a vulnerary on the second- 
ary lesions which have been caused by scratching. It may be 
used two or three times daily on the dry scalp. In the case of 
females with long hair we have a more complicated condition of 
affairs to deal with. The hairs are frequently full of ova, and 
these must be eliminated pan passu with the destruction of the 
pediculi. For this purpose a thorough shampoo with sapo viridis 
is unexcelled as it dissolves the nits and cleanses the hair. When 
the hair and the scalp have been thoroughly dried the same 
remedy as mentioned above may be used. A preparation which 
has met with success in Russia, not only in pediculosis, but 
scabies as well, is the thorough use of benzine. Its disagreeable 
odor, however, will always limit its use. The remedies which 
have been successfully used in pediculosis are numerous, and all 
have been highly lauded. A solution of bichloride of mercury 
varying in strength from 1 to 1000 to 1 to 5000 is well spoken 
of, also an infusion of staphisagria thoroughly applied. The use 
of coal-oil is popular with the lower classes, but is often fol- 
lowed by a marked dermatitis frequently of an eczematous char- 
acter. Solution of creolin, of the strength of eight per cent, is 
claimed to be efficient. A six per cent, solution of carbolic acid 
is an effective lotion in pediculosis, but it generally permits the 
ova to hatch, and a new crop of parasites to appear. The prin- 
cipal point to observe, no matter what measures be adopted, is 
that the treatment be thorough, and this implies not only the 10 
application of the remedy to the affected parts so as to reach 
every point, but also a frequency sufficient to accomplish the pur- 
pose completely, and not such as will permit of relapses through 
the hatching of the undestroyed ova. 
PEDICULUS CORPORIS. 
Pediculosis corporis is an affection which is produced by the 
pediculus corporis seu vestimenti. It is common enough to be 
seen under circumstances in which masses of individuals congre- 
gate, and have no opportunities or inclinations to keep them- 
selves clean. Soldiers who are any length of time in camp, labor- 
ers who live in camps, several occupying one tent, the dwellers of 
tenement houses of the lower class, and similar individuals seem 
to be infested with the body louse. As a rule, it is'adults who 
are most subject to the trouble, and men more frequently than 
women. The itching which is present is intolerable, and is most 
severe about the shoulders and sides of the body, although the 
limbs and trunks are often the seat of pruritus. The head is 
never attacked, and this will be immediately explained when we 
consider that the habitat of the pediculus corporis is the clothing 
and not the integument. The lesions presented upon the body are 
almost pathognomic of the trouble, and, when found, should 
always lead to a careful examination of the clothing worn next 
to the skin. The objective phenomena which are seen consist of 
secondary lesions, and these are, for the most part, excoriations 
of a marked character four to six inches in length, and several in 
number parallel to each other. They are the result of scratching, 
and to be found in those portions most accessible to the hands, 
viz., the scapular regions, the flanks, the buttocks, the outer sur- 
faces of the thighs, etc. The scratching, at times, is so severe 
as to produce bleeding and consequent crusts. If the trouble 
be superficial, ulcers will form. The underwear will stick to the 
denuded patches, and its removal will lead to fresh bleedings ac- 
companied by pain. When a case has progressed thus far the 
arms will share in the general involvement, and the spectacle pre- 
sented by a patient thus affected is that of a most miserable 
being. 
Among the modifications observed in the subjective symptoms 
occurring in pediculosis corporis is the presence of short and 
jagged scratch marks, due to digging of the nails into the integu- 
ment. Another condition is seen which should not be hastily 11 
misjudged. This consists of pigmentation of a light or dark 
brown color, at first disseminated in macules of varying size. In 
cases of long standing it may become diffuse and involve the en- 
tire integument which has been subjected to the depredation of 
the parasite. 
The pediculus corporis is the largest of the pediculi. It some- 
times attains comparatively enormous proportions and is quite 
voracious, abstracting the blood of its host quite freely and in 
amounts that are comparatively large. It is stoutly built, the 
female being considerably larger than the male. It varies in size 
from I'" to 2"' in length, being'about one-third as broad. In color 
it is a dirty-gray which has a reddish tinge after it has abstracted 
blood. The female is much broader at the abdomen on account 
of the ova which it must contain. It may be distinguished from 
the male by the notch which exists at the distal end of the abdo- 
men. This parasite is provided with three strong four-jointed 
legs, having claws at their extremities and provided with hairs. 
The abdomen has seven well-defined notches on each side. The 
head is large and somewhat acorn-shaped, the eyes being quite 
prominent. The antenna? which are strong, are five-jointed and 
very mobile. The mandibles are unusually powerful and easily 
cut the integument of the host. As mentioned above, the para- 
sites live in the seams of the clothing and it is here that the 
female deposits her ova which hatch in five or six days. It is said 
that in eighteen days they will reproduce. When the parasite de- 
sires food it will roam on the skin, and it is on this account that 
very few are ever found outside the clothing. 
The treatment of this condition is very simple in principle, but 
it is not such an easy matter to carry out in actual practice. It 
is to be divided into two parts-the treatment of the patient and 
that of his clothing. A good bath and destruction of the cloth- 
ing is certainly not difficult to order, but it cannot be carried out 
in many instances. What can be done, however, and if it be 
done thoroughly it will result in success, is to adapt the means 
to be used to the conditions presented. The treatment of the 
patient should consist in the application of campho-phenique 
to the entire affected surface. This remedy kills whatever 
parasites may be lurking on the skin, and it acts as an an- 
tiseptic and vulnerary, promoting a rapid healing of the der- 
matitis which has been excited by the scratching. Washing 12 
thoroughly with a slightly alkaline soap and then applying a 
1 to 1000 solution of bichloride of mercury is also a good 
plan. No method, however, will be effective unless uninfected 
clothing be assumed after its use. If, as it often happens, the 
patient has no change of clothing, the parasites must be picked 
out of the garments and killed, a matter which is easy, as they are 
found with but little trouble. To insure the destruction of the 
ova it is absolutely necessary to subject the clothing to a high de- 
gree of heat. It is better after this to soak it in a fairly strong 
alkaline solution and boil it and then thoroughly wash it. Such 
a course will rid the patient of these parasites; but, unless he 
avoids those persons or localities where body lice flourish, he will 
acquire them again. They may be picked up occasionally, as in 
the case of head lice, in public conveyances, sleeping cars, unclean 
hotels; or, in fact, wherever perfect cleanliness does not reign, 
and where all sorts and conditions of individuals may congregate, 
or occupy furniture which will be occupied by others. 
PEDICULUS PUBIS. 
Pediculosis pubis is an affection much more commonly en- 
countered in males than in females. It manifests itself by an 
intense itching about the mons veneris, which scratching does not 
seem to allay by any means. Beginning with fugitive sensations 
of pruritus, the symptom after some time becomes incessant and 
well nigh intolerable. Should the symptom be permitted to go 
on untreated for a protracted length of time the itching ceases 
entirely or almost so, although the parasite will continue increas- 
ing its numbers. It is not entirely limited to the pubic region. 
It may occur wherever there are coarse or stout hairs and it may 
affect individuals at all ages, from infancy to old age. It is not 
infrequently found about the hairs of the legs, if these be at all 
coarser than the ordinary languo hairs. The hair of the chest 
and of the axillae also afford a convenient nidus for the parasite. 
The beard is occasionally seen to harbor it as well as the eye- 
brows and eyelashes. But here it stops. The scalp is never 
affected*, as the hair of the head is doubtless too fine to afford 
the grasp which doubtless the parasite needs. So far as second- 
* In Nov. 1892, Rona presented a known exception in the case of a boy of 14 who 
presented pedieuli and their ova on the head, neck, eyebrows and eyelashes. The 
migrations of all the forms of pedieuli have been mentioned by several authors, but 
they are the exception rather than the rule. 13 
ary symptoms are concerned we And little or any occurring except 
in the axilhe and eyelids. In the former excoriations and poly- 
morphous eruptions occur; whereas, in the latter, a condition re- 
sembling tinea tarsi is developed as a result of the rubbing occa- 
sioned by irritation. Bluish macules are sometimes seen upon the 
anterior and upper portions of the thighs, due to the bites of the 
pediculi. These taches bleudtres, as they have been denominated, 
are pathognomic of pediculi pubis and are supposed to be due to 
a fluid ejected by the parasites when they prepare to exercise 
their depleting power. The macules disappear spontaneously 
and seem to occasion no subjective symptoms whatever in the 
patient beyond more or less fright at their apparently sudden ap- 
pearance. 
The pediculus or phthirius pubis,* or as it is commonly known, 
"the crab-louse, " is of a light-greyish color almost translucent at 
times. Size of the pediculi vary from I'" to 1'". The thorax is 
almost imperceptible, the form depending more upon that of the 
abdomen which has been very aptly denominated shield-shaped. 
It is provided with small eyes which show up quite distinctly. The 
antenna? are rather long and five jointed. There exist six four- 
jointed legs, the two last of which are provided with large, strong 
claws bearing a close resemblance to those of the lobster. These 
claws are so muscular, that in efforts to dislodge the parasite from 
a hair the hair itself is frequently pulled out. In addition to the 
legs which have been described, there exist eight teat-like pro- 
jections in the sides of the abdomen, these being prehensile feet 
provided each with four to ten hairs. The female, as is usual in 
this family of parasites, has a notch at the extremity of the ab- 
domen. Reproduction is very rapid, the ova being hatched out 
in six to eight days. The ova are goblet-shaped and so strongly 
attached to the hairs, that after hatching the shells will remain 
in situ. These are more or less translucent and exist along 
the shaft of the hair in varying numbers. The difficulty of dis- 
lodging them is frequently a cause of relapses so frequently seen 
in the affection. The grown specimens are unusually voracious in 
their habits and endowed with more than ordinary vitality. They 
lie flat against the skin with great tenacity, by means of the four 
pairs of short feet with which they are provided, and being very 
♦Among the names applied to this parasite may be mentioned phthrrius. inguin- 
alls, phthirius pubis, and morpio. 14 
pale in color they frequently escape detection and must be liter- 
ally scraped off in order to be distinctly seen. When in search 
of food they range about, most generally through the medium of 
hairs, although the clothing also acts as a carrier and transports 
them quite some distance from their original habitat. Occasional- 
ly ova are directly transplanted to new quarters by means of the 
finger nails. 
The treatment of pediculosis pubis is not always as easy as 
some would have us fondly imagine. When the trouble is con- 
fined to the pubic region it is not difficult to obtain a successful 
result; but when it has been disseminated over broad areas it re- 
quires care and attention to completely eradicate the little pests. 
The best method of treating the condition when it affects the eye- 
brows and eyelashes is to remove the pediculi and their ova with 
fine forceps. It is not a difficult thing to do and is always radi- 
cal in its results. 
As they are never present in great numbers, very little time is 
required, and all that is necessary may be done in one short sitting. 
So far as other parts of the body are concerned, any one of a 
number of methods may be successfully employed. A method 
which is very popular, but which is not only filthy but very fre- 
quently liable to bring on untoward effects, is the use of mercurial 
ointment. Other ointments are equally disagreeable to use and 
should be discarded in view of the fact that more cleanly and 
agreeable methods are always at hand. Lotions are certainly 
more desirable, but thoroughness should be observed in their use, 
not only for each application but for the length of time they are 
applied. They should be used twice a day for not less than eight 
days, as this will ensure the destruction of whatever parasites 
which may have been hatched out during this interval and will 
furthermore prevent the breeding of a new generation. An easily 
procurable lotion is a six per cent, aqueous lotion of carbolic 
acid. One which is of value when no excoriations exist is com- 
posed as follows: 
fj. Hydrag. bichlorid gr. iv. 
Aceti aromatic 5 vj. 
M. 
When excoriations or other secondary lesions exist, however, it 
has been my custom to employ campho-phenique, as it is not only 
an efficient parasiticide but it also acts beneficially as an antiseptic, 15 
procuring a rapid resolution of the artificial inflammatory process 
and is unaccompanied by any danger of producing toxic symp- 
toms. Moreover, it acts as an antipruritic and thus fulfills the 
requirements of an ideal remedy in this condition. 
PULEX IRRITANS. 
The cutaneous trouble occasioned by the pulex irritans or com- 
mon flea is one which frequently gives rise to groundless fears 
and alarms. The lesions which appear as results of the bites of 
this parasite are erythematous in character, a number of them 
appearing like roseola and liable to be mistaken for measles. The 
lesions may be discrete and few in number or there may be many 
of them distributed over comparatively a large area of the inte- 
gument. At the time the flea bites there is a sharp stinging sen- 
tion, which gives way in a comparatively short space of time to 
burning and itching of a rather severe character. If the lesions 
be numerous these subjective sensations are intensified in charac- 
ter, and the efforts made to subdue them will result in secondary 
lesions. The diagnosis is not a difficult one to make if the 
lesions be closely examined. No matter what secondary lesions 
are present, the primary macules will always exist here and there. 
Each one of these has a central punctum which is minute in size 
and darker in color, besides being generally elevated above the 
general surface of the macule. It is due to a haemorrhage and 
the small clot of blood can be distinctly made out with the help 
of a magnifying glass and can be even removed with the point of 
a needle. This will serve to distinguish the eruption from the 
different forms of roseola. Whilst fleas are not essentially human 
parasites, they seem to have a fondness to adopt the human body 
for a host, and although not frequently seen in this country they 
are common enough in the rural districts of Europe, where dogs, 
cats and human beings herd together in small, close, filthy 
quarters. 
The pulex irritans is quite familiar to all who have ever owned 
cats or dogs. It possesses a large abdomen, small thorax and 
roundish head provided with small eyes. It is a light brown in 
color when mounted, but as found when living it is of a marked 
dark brown and very glossy in appearance. It varies in length 
from to iy". It has well marked five-jointed antennae and is 
provided with six legs. These latter organs are peculiar in that 16 
they are three-jointed, the last joint, however, being terminated 
by a toe which has five joints and which itself terminates in two 
claws. This last toe and joint are well provided with bristles, 
located on the posterior surface. The last pair of legs are much 
longer and stronger than the two anterior pairs and they are very 
powerful and muscular, thus enabling the animal to leap and pro- 
ject itself through comparatively long distances. Again, we find 
that the three pairs of legs are much crowded anteriorly, but fold- 
ing in such a manner that when the flea is at rest the abdomen is 
apparently held midway. The animal is quick of movement, not 
only when it is hopping but also when it is running, which it does 
upon the slightest indication of danger or disturbance. Its 
favorite roaming ground is close to the skin, in animals, where it 
is buried in the thick growth of fine hair. Here it is that it per- 
forms its depredations, preferring those regions where the skin is 
thin, such as at the flexures of the joints. When it attacks the 
human it generally seeks those regions which are covered by 
clothing and warm, and never attacks the scalp. The neck is 
frequently sought by them, in men, perhaps on account of the 
attraction furnished by the white color of the collar. The pulex 
irritans breeds very rapidly and, so far as I have been able to de- 
termine, it deposits its eggs on the skin and they hatch out in 
about a week. 
The treatment of flea-bites is perhaps not so important as the 
adoption of prophylactic measures. For the former a number of 
adequate applications may be used, and one of the best perhaps is 
an aqueous solution of some antipruritic such as the following: 
1$. Hydraggyri bichloridi gr. ij. 
Ammon. Muriat gr. iv. 
Acid, carbolici 5 ij* 
Glycerini - ij. 
Aqate rosae q. s. ad. « vj. 
M. 
This should be applied several times in the day and a quick re- 
covery will result. But it will scarcely prove efficient unless the 
skin is freed from the little pest which causes the trouble. 
To accomplish this the clothing should be carefully removed and 
exposed to the air, and a carefulness exercised that the fleas will 
not leap into other articles of clothing. If there be pets about 
the house see to it that the cats and dogs are freed from parasites, 
and if they have been acquired from strange animals, avoid them Pediculus Corporis. 
Pediculus Pubis. 17 
in the future. To keep animals free from fleas is a most difficult 
matter, but the parasites may be killed by rubbing in well some 
pyrethrum powder, which destroys them and is not noxious to the 
host. Bathing dogs with carbolic soap will rid them of fleas if 
care be taken to submerge them complntely so that the parasites 
will be carried off in the water. But I do not desire to enter 
into the subject beyond calling attention to the fact that many 
cases of flea-bites occur in patients in which the diagnosis must 
be made from the lesions, as the parasite has long since betaken 
itself to new fields and cannot be found. It is for this reason 
that great care should be taken not to mistake flea bites for ex 
anthematous troubles, and vice versa. 
CIMEX LECTULARIUS. 
The cimex lectularius or "bed bug " is almost universally dis- 
seminated, and occasions lesions which give rise to considerable 
alarm, and which are frequently wrongly interpreted, this being 
one of their peculiarities. The parasite occasions much discom- 
fort by its bite, and it requires a certain amount of attention to 
make a proper discrimination. The most severe lesions are found 
in those who have the most tender skins, and the subjective 
symptoms also vary in proportion to this factor. In infants and 
children, more especially, the lesions are apt to take on an in- 
flammatory appearance, whereas in adults who have particularly 
resisting integuments scarcely any perceptible objective symp- 
tom is to be seen. On the other hand, those whose skins are 
most susceptible are conscious of a sharp pain with a slight dull 
aching sensation following, the pruritus not being so severe as 
those whose epidermis is thick, and in whom the itching oc- 
casioned by the bite of the parasite is intolerable. The particular 
lesion caused is a small circumscribed oedema with a minute central 
punctum, which is haemorrhagic. The lesions are of the size of 
the small finger nail or even smaller, and resemble the wheals of 
uticaria with the exception of the outer erythematous zone. In 
the bite of the bed-bug they are white, and furthermore are more 
persistent. In any case, the pruritus excited lends to the forma- 
tion of secondary lesions brought on by the scratching. Any 
portion of the body may be the seat of the eruption, although, as 
a general rule, the hands, wrists, feet, ankles and face are those 
most frequently involved, as they are the most accessible locali- 18 
ties. It is no uncommon thing to be awakened out of a sound 
sleep by a pruritus of such an intense nature as to deprive the 
subject of rest, and a close inspection will reveal a cimex as the 
cause of the trouble. The constant subjection to the irritation 
nightly is very apt to bring on a train of nervous symptoms, and 
reflex excitability which may be incorrectly interpreted unless the 
true cause be discovered. 
The cimex lectularius, acanthia lectularia, or common bed-bug, 
is probably one of the best known animal parasites which atttacks 
the human being. Its geographical distribution is almost uni- 
versal, the varieties found in the tropics being much larger than 
those encountered in temperate zones. When fasting the cimex 
is flat, of a yellowish-red color, and varying in length from 1"' to 
2'". When glutted with blood it has a distinct red color, and is 
appreciably enlarged by the blood which it contains. It is un- 
usually tenacious of life, being able to exist for protracted periods 
of time without food. When it has an opportunity, however, it 
is gluttonous. It has a penetrating odor, disagreeable in the ex- 
treme, although compared to cinnamon by some. The parasite 
has a large abdomen, a small thorax, and a diamond-shaped head, 
the eyes being fairly large and prominent; two antennae, which 
are four-jointed and very mobile, project anteriorly. There exist 
three pairs of legs, three-jointed in character, and terminating in 
a single claw. The body is provided with a number of bristles, 
none, however, being perceptible on the legs. The female pro- 
liferates not only frequently, but large broods are the result. 
The young as soon as hatched begin their depredations, and as 
they are often not larger than a very small pin's head they fre- 
quently escape detection, although the odor reveals their pres- 
ence. The habitat of the bed-bug is in the cracks of the wood 
of bedsteads, in the bed-clothes, under wall-paper, in old books, 
in fact wherever a small chink or crack can afford them a hiding 
place. They are not infrequently found in the clothing, having 
wandered there from the cracks of clothes-presses or wardrobes. 
As a rule, the bed-bug attacks his host when the latter is asleep, 
and the attacks of the parasite are always fierce. The irritation 
produced is not only caused by the direct wound inflicted, but 
by the injection of an acid fluid which is intended to prevent the 
coagulation of the blood as it is drawn. It is for this reason 
that micro-organisms are apt to be injected by the parasite into 19 
lymphatic spaces, and thus infection be produced without any very 
clear cause for it. 
The treatment for the cutaneous trouble caused by the cimex 
is usually a simple one so far as allaying the symptoms is con- 
cerned. Dilute alkalies, vinegar, alcohol, whisky, etc., are the 
more commonly recognized domestic remedies. It is best, how- 
ever, to use a dilute solution of bichloride of mercury, as it will 
not only cause the disappearance of the symptoms, but will act 
as an antiseptic, and prevent any possible phlegmonous compli- 
cations. Campho-phenique will do the same thing, and possesses 
an added advantage in being an anaesthetic. Treatment may be 
deemed superfluous when one or two small lesions exist, but 
when an infant is affected from head to foot it becomes a matter 
of some moment, as the result of such an extensive cutaneous ir- 
ritation may take on a serious character. It is also for this rea- 
son that care should be exercised not to mistake the trouble for 
irritation or some exanthem. The principle thing to do, however, 
is to get rid of the "bugs." This is not such an easy matter as 
it might seem, as every housekeeper will testify to. To rid fur- 
niture of bed-bugs is possibly yet a problem, for the females de- 
posit their ova in minute cracks which are difficult to reach with 
parasiticides. Mercurial preparations are probably the best for 
this purpose, and yet they are fraught with some danger to those 
sleeping in the bed so treated. Moreover, whilst the bedstead 
may be clean the seams of the mattresses will be found teeming 
with these pests, and a thorough and careful search for, and de- 
struction of them seems to be an almost hopeless and intermin- 
able piece of work. The only thorough method, perhaps, is to 
have everything new, and to live in quarters free of the cimex. 
DERMANYSSUS AVIUM. 
The eruption caused by this parasite is rarely, if ever, seen in 
cities, although it is not of unusual occurrence in the country. 
It produces an eruption most often upon the dorsum of the hands, 
about the wrists and forearms, although other portions of the 
body are liable to be attacked. The attack generally begins with 
itching, which is soon followed by an eruption more or less dif- 
fused, and which may be erythematous and papular, or mixed, 
vesicles and wheals making their appearance. It is seen in those 
who come in contact with domestic fowls, and the parasite is 20 
ordinarily derived from the chicken-house. The trouble is often 
very annoying, and aggravation is by no means uncommon from 
repeated exposure to the cause. Women and children suffer 
more severely from this cause than men on account of the greater 
delicacy of their skin. The peculiar localization of the eruption, 
together with its strict limitation, should immediately arouse sus- 
picion, more especially when observed in those whose duties cause 
them to frequent chicken-houses or aviaries. 
The dermanyssus avium, or chicken louse, as it is more com- 
monly known, is a familiar parasite to those who raise chickens, 
and it is an enemy whose destruction is constantly sought on 
account of its fatal effects on poultry. It is about 1"' long and 
perhaps one-third as broad. It is rather pale in color. Its ab- 
domen is quite long in proportion to the entire body and its head 
is somewhat mushroom-shaped and provided with two rather 
small but distinct eyes. It has no antennae, but is provided with 
powerful mandibles. It has three pairs of three-jointed legs 
which, like the body, are not provided with bristles. This para- 
site is very prolific and voracious, attacking not only common 
fowl but pigeons and other domesticated birds, and extending its 
depredations even to quadrupeds. It is chiefly found in the wood- 
work of houses, where it issues at night to feast upon the sleeping 
fowl. A number, however, will remain on their host, and it is 
chiefly in the flexures of the joints and upon the neck that they 
are to be found. Young birds will not infrequently die of the 
exhaustion induced from the drain of blood, and the older ones 
become emaciated. 
The treatment of the eruption caused by the chicken louse is a 
very simple one, consisting of the application of a three per cent, 
solution of carbolic acid, which rapidly allays all the symptoms. 
To prevent recurrences the infested chickens and their quarters 
should be avoided. If this avoidance cannot be effected, atten- 
tion should then be turned to the fowl and their habitation. For 
the former the use of carbolized oil, pyrethrum powder or dilute 
oil of orris will effectually rid them of the parasites. The build- 
ing in which they are kept can be rid of the parasites by washing 
with a solution of some strong alkali, such as common lye, and 
it is better, after this has been done, to thoroughly whitewash 
the structure within and without, having previously isolated the 
fowl and destroyed their parasites. Occasionally in the human Pedieulus Pubis, emerging from Ovum. 
Pulex Irritans. 21 
the parasite will be found upon the skin, but it does not seem to 
thrive upon the integument of man and it quickly disappears. 
IXODES AMERICANUS. 
The lesions occasioned by this parasite are of the most acute 
character and may result quite seriously. The subjective sensa- 
tions are of a painful, burning nature, whilst the lesions are of an 
inflammatory character. When observed it will seem as if the 
parasite is embedded in the skin, and surrounding the part in 
which it is buried there is a bright red areola with occasionally a 
small wheal. If the parasite is torn away a portion remains behind 
and a slight phlegmonous process results, generally leading to 
suppuration and final resolution. The genital region seems to be 
particularly affected, although the lower limbs are also attacked 
to quite a considerable degree. The trunk and upper extremities 
are also subject to the depredations of this troublesome parasite. 
Males are more subject than females on account of their outdoor 
life and occupations. 
The ixodes Americanus (amblyoma Americanum) or wood-tick, 
as it is ordinarily known, is about the size of the cimex lectu- 
larius and has the same general form. It is red in color and has 
a rather small head and distinct, small eyes. The variety most 
commonly encountered has a white spot situated about the center 
of the back. It is provided with three pairs of three-jointed legs 
provided with a single claw. The most prominent feature is the 
powerful suction apparatus which it possesses. This consists of 
three divergent, sharp, trunks, which are brought close together, 
driven into the skin, and then separated, thus giving a hold which 
will not relax. The efforts made to remove the tick result in 
tearing off the body, and thus leaving the embeddied portion to 
act as a foreign body on the skin. The tick does not limit its 
depredations to the human being, but attacks all quadrupeds upon 
whom it can secure a hold. It seems to be most plentiful in 
dead leaves, rotten wood, and vegetable matter undergoing dry 
decay. It is quite prolific, and individuals travel together in 
great numbers, so that is not rare for several hundred to fasten 
themselves upon one host. So far as the treatment of the 
condition caused by this parasite is concerned, it is a 
very simple matter. To get rid of the parasites it is merely 
necessary to apply olive oil liberally wherever they are to be 22 
found. The action of the oil is two-fold-it causes the ticks to 
fall out and acts as a soothing remedy to the wounds they have 
produced. If they have already been torn off, a mixture of equal 
parts of olive oil and campho-phenique will act very satisfactorily; 
so wrill carbolized oil of a strength of about two per cent. As 
regards prophylaxis, it is well nigh impossible to attain. Oil of 
pennyroyal and other essential oils will not prevent ticks from 
attacking the skin. It may keep off a certain number, but indi- 
viduals are so voracious that after a tramp through the woods 
they will be found and their locality will not be difficult to estab- 
lish. The only prophylactic that is certain is to avoid the locali- 
ties where they hold forth. 
I do not propose delaying with any more parasites of an ani- 
mal nature which infest the human skin. This would be an 
almost endless task, as the list is very large. A few which might 
be mentioned are the chigoe or chigger, the leptus autumnalis, 
the filaria Medinensis or guinea-worm, the screw-worm, etc. The 
tropics have their peculiar animal parasites, which are numerous 
and produce serious lesions, so serious that they even may be 
fatal in their effects. Suffice it to say, that those which I have 
given are the ones most commonly met with in our latitudes, and 
sufficiently numerous to satisfy any ordinary demand in that 
direction. 
For the benefit of those those who may be desirous of prose- 
cuting their studies still further in this direction, I append a list 
of a few monographs devoted to the subject of animal parasites 
which infest the skin. 
BIBLIOGRAPHY. 
Giebel.- " Insecta Epizoa," Leipzig, 1874. 
Van Beneden. - "Animal Parasites," London, 1876. 
Piaget.-"Les Pediculines," Leyden, 1880. 
Megnin.-"Les Parasites et les Maladies Parasitaires," Paris, 
1880. 
Languetin.- " Notice Snr la Gale," etc., Leipzig, 1861. 
Languetin. - " Notice Snr la Gale," Paris, 1859. 
Fuerstenberg.-" Die Kratzmilben, " etc., Leipzig, 1861. 
Kuechenmeister. - "Animal and Vegetable Parasites of the 
Human Body," London, 1857. 
Packard. - "Guide to the Study of Insects," New York, 1878. 23 
Anderson (McCall). - "On the Parasitic Affections of the 
Skin," London, 1863. 
Startin (J. J.)-"Lectures on Parasitic Diseases of the Skin," 
London, 1881. 
Alberti et Gorn.- " De Scabie, " Halle, 1718. 
Alibert. - " Monographic des Dermatoses," 1834. 
Alt.-"Dissert, de Phthiriasi," Bonn, 1824. 
Besnier. - " Affections Parasitaires, " Paris, 1884. 
Cartot, C. - " Les Parasites Penetrants de la Peau," etc., Bor- 
deaux, 1885. 
Colsmann, A. A. - "De Parasitis Corporis Humani," Berlin, 
1859. 
Fox, W. T. - " Skin Diseases of Parasitic Origin, " London, 1863. 
Gudden, B. - "Zur Lehre v. d. durch Parasiten bedingten 
Hautkrankheiten, " Wurtzburg, 1863. 
Hereau.-"Des Parasities Cutanees de 1'Homme," 1842. 
Jeffries, J. B.-"Animal and Vegetable Parasites of the 
Human Skin and Hair," Boston, 1872. 
Kleinhans, L.-" Die Parasitaren Hautkrankheiten," Erlangen, 
1864. 
Le Roux. - " Traite sur la Gale," Paris, 1809. 
Moinez. - "Les Parasites de 1'Homme," Paris, 1888. 
Reydellet.- "La Maladie Pediculaire," Paris, 1802. 
Van Vliet.-"Dermic Parasites," Washington, 1879. 
Zurn. - "Die Thierischen Parasiten," etc., Weimar, 1872. 
Weyl u. Geber. - "Die Parasitaren Hautkrankheiten," Leipzig, 
1884. 
This embraces but a very small proportion of the books and 
monographs devoted to single animal parasites or to the entire 
subject, but it is sufficiently extensive for all practical purposes. 
Before concluding, I desire to express my thanks to Dr. A. S. 
Barnes, Jr., for help in making some of the microphotographs 
appended to this article. COMMERCIAL PRINTING CO., ST. LOUIS. Cimex Lectularius. 
Chicken Louse.